1. Field of the Invention
This invention relates to ventilation systems for vehicles, and in particular, to adjustable air vents for snowmobiles for adjusting an amount of ambient air permitted to flow into engine compartments of the snowmobiles.
2. Description of the Related Art
Recreational vehicles and more particularly snowmobiles, generally operate in cooler ambient temperatures. As such, air cooled engines (usually 2 cycle) are often used as a power source. In some newer models of snowmobiles, liquid cooled engines (either 2-cycle or 4 cycle) having heat exchangers are also used. It is generally necessary to have an inflow of air (called “ram air”) into the engine compartment to either cool the heat exchanger for the liquid cooled engine or to flow pass and remove heat from the cooling fins of the air cooled engine.
It has been found, however, that when the snowmobile operates at extremely cold temperatures, the engine can be so overcooled by the inflow of ram air, that its efficiency decreases. Furthermore, when operating in deep snow, snow may enter through the ventilation openings into the engine compartment and again overly cool the engine or adversely affect other mechanical systems. For instance, the snow can contact hot surfaces of the engine and melt or turn to steam. The melted snow or steam can then come into contact with cold surfaces and refreeze. The resulting buildup of ice can prevent proper operation of the vehicle systems, including, for example, the torque converter.
Thus, there is a need to have adjustable ventilation vents that can be quickly and easily opened and closed by an operator without tools and preferably, while wearing gloves or mittens, during different conditions of operation.
Sliding-type air vents are known in the prior art. See for instance, Hansen, U.S. Pat. No. 1,638,847, issued Aug. 16, 1927. Hansen discloses a shutter for an automobile radiator having a first plate 10 with a plurality of slots 14 and a second plate 18 having a like number of slots 19. The two plates are slidably engaged with one another to allow plate 18 to be moved from a first position, where the slots 14 and the slots 19 are aligned and air can pass therethrough, to a second position, where the slots 14 and the slots 19 are not aligned and air does not flow therethrough. The sliding plate 18 is actuated via a remote pin 35 mounted to the automobile dashboard through actuating wires 31 and 32 positioned in tubes 33 and 34.
Pratt, U.S. Pat. No. 4,706,461, issued Nov. 17, 1987, discloses a similar sliding air vent. Pratt uses a thermoelongating actuator 82 mounted to levers 74 and 76 mounted between the stationary and slidable grills to vertically move the slidable grill to an opened or closed position, as desired.
However, neither of these prior art devices is simple enough or easily manually operated by an operator wearing gloves or mittens so as to be applicable to use in a recreational vehicle, and especially a snowmobile.